In the end, the people will speak out and respond to back-doors. In-fact we need FLOSS app stores right now (Similar to F-Droid[0], but baked in as the default store), and they need to be funded properly & they need sound economic incentives to continue. No more 'free' apps where you pay for them with your data. It's possible to have FLOSS apps that are not gratis where people pay for them with money, not their data.
(The reason I suggest we switch to FLOSS app stores is that the apps can easily be checked for back-doors or malicious code since the code is open source. It makes the apps readily available for audits too)